1. Field of the Invention
The present invention relates to the field of liquid crystal displaying, and in particular to a mounting structure of an optical film assembly.
2. The Related Arts
Liquid crystal displays (LCDs) have a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and are thus of wide applications, such as mobile phones, personal digital assistants (PDAs), digital cameras, computer monitors, and notebook computer screens.
Most of the liquid crystal displays that are currently available in the market are backlighting liquid crystal displays, which comprise an enclosure, a liquid crystal panel arranged in the enclosure, and a backlight module mounted in the enclosure. The structure of a conventional liquid crystal panel is composed of a color filter (CF) substrate, a thin-film transistor (TFT) array substrate, and a liquid crystal layer arranged between the two substrates and the principle of operation is that a driving voltage is applied to the two glass substrates to control rotation of the liquid crystal molecules of the liquid crystal layer in order to refract out light emitting from the backlight module to generate images. Since the liquid crystal panel itself does not emit light, light must be provided from the backlight module in order to normally display images. Thus, the backlight module is one of the key components of the liquid crystal displays. The backlight modules can be classified in two types, namely a side-edge backlight module and a direct backlight module, according to the site where light gets incident. The direct backlight module comprises a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED), which is arranged at the backside of the liquid crystal panel to form a planar light source directly supplied to the liquid crystal display panel. The side-edge backlight module comprises an LED light bar, serving as a backlight source, which is arranged at an edge of a backplane to be located rearward of one side of the liquid crystal display panel. The LED light bar emits light that enters a light guide plate (LGP) through a light incident face at one side of the light guide plate and is projected out of a light emergence face of the light guide plate, after being reflected and diffused, to pass through an optic film assembly so as to form a planar light source for the liquid crystal panel.
With the popularization of bezel slimming of the liquid crystal displays, how an optical film assembly is mounted becomes extremely vital. Poor mounting may readily lead to poor homogeneity of backlighting and even leaking of the backlighting.
Referring to FIGS. 1 and 2, schematic views are given to illustrate a mounting structure of an optical film assembly at the light-incident side and non-light-incident side of a backlight module. The optical film assembly 700 is mounted under a mold frame 900 for both the light-incident side and the non-light-incident side. The mold frame 900 has a cross-sectional shape that is of a stepwise configuration having a bottom 901 and a step 903. The bottom 901 is a flat surface pressing down the optical film assembly 700 to achieve mounting of the optical film assembly 700. The step 903 carries and supports a liquid crystal display panel thereon. Such a mounting structure of the optical film assembly 700 is relatively simple; however, with the bezels of the liquid crystal display devices getting slimmer, the distance that is available for the mold frame 900 to hold and mount the optical film assembly 700 is getting shorter and this makes the optical film assembly 700 susceptible to detaching from the underside of the mold frame 900 so that optical issues including light leaking and inhomogeneity of brightness may occur.
Referring to FIGS. 3 and 4, schematic views are given to illustrate another mounting structure of an optical film assembly at the light-incident side and non-light-incident side of a backlight module, which is different from the optical film assembly mounting structure discussed above that the optical film assembly 700′ is mounted above the mold frame 900′ for both the light-incident side and the non-light-incident side. The mold frame 900′ has a cross-sectional shape, which is of a dual-stepped configuration, comprising a first step 901′ and a second step 903′. The first step 903′ has a flat surface 905 and the optical film assembly 700′ is positioned on the flat surface 905. The first step 901′ supports the optical film assembly 700′ and the second step 903′ carries a liquid crystal display panel. Mounting the optical film assembly 700′ in such a way, although overcoming the optical issues of light leaking and inhomogeneity of brightness, requires a complicated mounting structure, making the assembling process tedious and extended and the manufacturing performance poor.